Flood Watch in effect for Squamish

The River Forecast Centre has upgraded to a Flood Watch for the South Coast and Sea to Sky including areas around Squamish, Whistler and Pemberton, Sunshine Coast, Howe Sound and the North Shore Mountains.

A Flood Watch means that river levels are rising and will approach or may exceed bankfull.

Details:

The first of a series of storms has arrived on the South Coast. The storm is bringing heavy
rainfall, with rainfall totals forecast to range between 40‐70mm over the Fraser Valley and 50‐
80mm over the North Shore Mountains and Howe Sound, with higher amounts possible over
higher terrain.

A subsequent atmospheric river event is forecast for the weekend with precipitation arriving
mid‐day on Saturday. Rainfall totals are expected to be higher for the weekend event.
Additionally, temperatures will be warmer resulting in higher freezing levels. There is a greater
risk for a rain‐on‐snow event to melt much of the current snowpack, adding additional water
into rivers and creeks.

A third atmospheric river is forecast to reach British Columbia next Tuesday/Wednesday (November 30 to December 1). It is still too far into the future to provide exact details regarding the impacts and severity of this third storm.

Rivers are expected to see rises on Thursday in response to the first rainfall event, with the
potential for highest flows (2‐year to 5‐year) expected around the Sunshine Coast, Howe Sound
and North Shore corridor. Rivers in the Fraser Valley are expected to see rises, though currently
these are expected to be more typical in magnitude for fall storms, however these may be more
problematic to flood response and recovery efforts and damaged infrastructure in the region.

The second system arriving over the weekend will likely be more problematic. It is currently
forecast to have higher rainfall totals, warmer conditions resulting in additional snowmelt and
will occur immediately after the current storm system. There is potential for flows to reach 10‐
year to 50‐year levels (or higher)– likely occurring Sunday or Monday.

The public is advised to stay clear of the fast‐flowing rivers and potentially unstable riverbanks
during the high‐streamflow period.

The River Forecast Centre continues to monitor the conditions and will provide updates as
conditions warrant.

Stay tuned to the River Forecast Centre for updates.

November 25, 2021